A representative one of thin-films is a DLC thin-film. The DLC thin-film is an abbreviation of a Diamond Like Carbon film, and refers to a carbon film having physical properties like diamond, e.g., having high hardness. In the related art, a DLC coating using the DLC thin-film has been widely used as a protective thin-film for a variety of dies or tools. In this case, the DLC thin-film can be easily formed on the die or the tool depending on its type, shape and size, but may be very difficult to be formed. On a surface of the die or a surface adjacent to a tip of the tool, the DLC thin-film is easily formed. On the other hand, on an inner peripheral wall facing to an outer peripheral wall of a punch used for drawing, for example, the DLC thin-film is very difficult to be formed.
However, even though it is difficult to be formed, it is often necessary to form the DLC thin-film. In particular, as to a progressive die for drawing or a transfer mold die, there are a number of dies each having a die inner peripheral wall having a small inside diameter. In order to assure soundness of a whole die for a prolonged period, it is essential that the DLC thin-film is formed on the die inner peripheral wall.
In the meantime, as a device for forming the DLC thin-film, there is a sputtering device for forming a film (hereinafter may be referred to as “a first device in the related art”) characterized in that it comprises a magnet mechanism for setting a magnetic field that leads ionized sputter particles to an object to be processed; the sputter particles being ionized in plasma formed in an ionizing space between a target and an object holder (Patent Document 1). A sputtering device for forming a film (hereinafter referred to as “a second device in the related art”) characterized in that it comprises a magnet mechanism disposed at a rear side surface viewed from a target is also known (Patent Document 2). An object of the first device in the related art or the second device in the related art is to prevent plasma from diffusing by the action of the magnetic field, thereby arriving high density plasma at the object.
Patent Document 1: Japanese Patent Application Laid-open No. 2006-307243 (paragraph 0037, FIGS. 1 and 2)
Patent Document 2: Japanese Patent Application Laid-open No. Hei10-259480 (paragraphs 0047 to 0050, FIG. 5)
Although the first device in the related art or the second device in the related art can increase the density of the plasma, it cannot fully meet the needs that the thin-film is formed on a die inner peripheral wall having a small inside diameter or an inner periphery of a tool having a small diameter hole. Because simply increasing the density is insufficient in order to reach plasma within the small diameter hole, in particular to deeper positions, an aggressive means for converging and leading the plasma at a desired area is necessary.